This dataset provides information about the position, position accuracy, mark name, mark type, condition and unique four letter code for geodetic marks in terms of a New Zealand's official geodetic datum.
The dataset only contains marks that are within the New Zealand mainland and offshore islands. These positions have been generated using geodetic observations such as precise differential GPS or electronic distance and theodolite angles measurements. The positions are either 2D or 3D depending of the availability of this measurement data.
The source data is from Toitū Te Whenua Land Information New Zealand's (LINZ) Landonline system where it is used by Land Surveyors. This dataset is updated daily to reflect changes made in the Landonline.
Accuracy ============ Geodetic marks with a coordinate order of 5 or less have been positioned in terms of NZGD2000. Lower order marks (order 6 and greater) are derived from cadastral surveys, lower accuracy measurement techniques or inaccurate historical datum transformations, and may be significantly less accurate.
The accuracy of NZGD2000 coordinates is described by a series of 'orders' classifications. Positions in terms of NZGD2000 are described by three-dimensional coordinates (latitude, longitude, ellipsoidal height). The accuracy of a survey mark is indicated by its Order. Orders are classifications based on the quality of the coordinate in relation to the datum and in relation to other surrounding marks. For more information see http://www.linz.govt.nz/geodetic/datums-projections-heights/heights/coordinate-orders/
Note that the accuracy applies at the time the mark was last surveyed. Refer to the web geodetic database for historical information about mark coordinates.
Note also that the existence of a mark in this dataset does not imply that there is currently a physical mark in the ground - the dataset includes destroyed or lost historical marks. The geodetic database provides more information on the mark status, valid at last time it was visited by LINZ or a maintenance contractor.
The original data comes from a geodetic database which was managed by LINZ and its predecessors.
This database contained a summary of the mark, coordinate and site information derived from survey observations and field sheets. The database was migrated into Landonline in 2000.